It had all the makings of a dream come true. A deep-pocketed investor was willing to fork over $1.5 million over three years to help the design duo Costello Tagliapietra grow their fledgling business.

In return, the designers, who are based in Brooklyn and favor flannel lumberjack shirts, would place their trademarks in a newly formed company of which they would own 30 percent. The investor, NRDC Equity Partners, would control the remaining 70 percent.

Negotiations dragged on for weeks and a final agreement was never reached. Ultimately, the designers were uncomfortable at the prospect of losing control of their name, among other issues, sources said.

The unraveling of the deal highlights a common problem for young designers: When to trade their name for much-needed cash.

The arrangement has not always produced happy marriages. Roland Mouret, Helmut Lang and Jil Sander are among those who lost the use of their names after falling out with investors.

“The question is what should you give up and when?” said Peter Arnold, the former executive director of the Council of Fashion Designers of America and now chief executive of Cynthia Rowley.

As the costs of starting a fashion house have spiraled, the issue is becoming one that designers increasingly have to face early in their careers when placing a value on their business is not always easy.

At the same time a growing number of private-equity firms have shown an appetite for investing in emerging designers who have the potential to strike it big, often insisting on control of the designer’s name to offset their considerable risks.

NRDC Equity Partners, meanwhile, is looking to build a stable of designer brands that it can sell through its recently acquired Lord & Taylor department store chain, and possibly other holdings such as Linens ‘N Things.